Which loss function should I use for binary classification?
There are several loss functions that you can use for binary classification. For example, you could use the binary cross-entropy or the hinge loss functions. See, for example, the tutorials Binary Classification Tutorial with the Keras Deep Learning Library (2016) and How to Choose Loss Functions When Training Deep Learning Neural Networks (2019) by Jason Brownlee. Have also a look at Keras documentation of its available loss functions.